Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 0f42b20f799c9d19…

MALICIOUS

Office (OLE) / .XLSX

69.6 KB Created: 2022-01-20 19:00:43 Authoring application: Microsoft Excel
MD5: 7e3dc40ab5a5a824a157f894d0b46768 SHA-1: 8bec0cec1e5b64d7e6dced82bcc0b9b62fa88b0d SHA-256: 0f42b20f799c9d1956f810952da2492e135ddaf0c1eb3afeb975a49ae8c784ef
140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is identified as malicious by ClamAV with the signature Doc.Downloader.EmotetExcel01220-9937164-0, indicating a known Emotet variant. Static analysis revealed the presence of Excel 4.0 macros, specifically an Auto_Open defined name, which is a common technique for initial execution. This macro likely serves to download and execute a secondary payload, consistent with Emotet's behavior.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • ClamAV: Doc.Downloader.EmotetExcel01220-9937164-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetExcel01220-9937164-0
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
7f1f89a8b36a750dced08313a4e4f056192a6eac7194357c673dbbd2670a1a18		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 4219 bytes

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